The issue log is a project document where the project manager records the concerns that might turn into potential issues. It is used to document and monitor the resolution of issues. The operations group’s concern, which could not be addressed and might turn into a potential issue, should be recorded in the issue log. This allows for tracking and managing the concern until it is resolved. References: 

https://www.projectmanager.com/blog/great-project-documentation

https://www.techrepublic.com/article/6-essential-documents-for-project-management-success/